Good evening as we come on the air cities around this nation are on heightened alert today a proud holiday in Boston patriots day Marathon Monday. Why shattered by bombs here's the video was the moment before it changed. And there. The first booming explosion. -- -- smokes you can hit the screens. People thrown into the ground. And their seconds later a second blast a ball of fire a block away. As half a million people lined the streets of Boston. So many was devastating injuries tonight and our ABC news team is ready to bring you the very latest we start with ABC's senior national correspondent. Jim Ottawa. Two hours after the winner's -- Four hours nine minutes into the race the amateur runners still -- Boston's Boylston street. Too rapid fire explosions at the finish. Turning to terrorist Boston Marathon. Into what one hospital official called a war. -- six mile marker. -- saw the first explosion happened and there are some commotion I saw fire and smoke. And I didn't know what it was demand from about needs. What that gentleman saving over there I would lose -- -- roads.

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